Phosphatic clay products for use as soil wetting agents, methods of delivery of phosphatic clays to soil, and phosphatic clay coatings for purpose of water retention

ABSTRACT

Phosphatic clays, and the use of phosphatic clays as a soil wetting agent. Phosphatic clays as wetting agents aid in the retention of water in sandy soil, and/or for prevention or reduction of leaching of nutrients. Due to its unique particle size and shape, phosphatic clay exhibits high water absorbing and retaining qualities. Further, phosphatic clay is readily available as a by-product of mining of phosphatic ore. The phosphatic clay wetting agents increases the effectiveness of the water applied to the soil, thereby reducing the amount of run-off, and reducing the amount of water needed to accomplish sufficient irrigation. The phosphatic clay wetting agents can be delivered to the soil as a sprinkle-on product, spray-on product, soil amendment, fertilizer or seed coating, or fertilizer composition.

RELATED APPLICATION

The present application claims the benefit of U.S. ProvisionalApplication No. 61/683,988 entitled PHOSPHATIC CLAY PRODUCTS FOR USE ASSOIL WETTING AGENTS, AND METHODS OF DELIVERY OF PHOSPHATIC CLAYS TO SOILand filed Aug. 16, 2012, which is incorporated herein in its entirety byreference.

FIELD OF THE INVENTION

The invention relates generally to phosphatic clays, and moreparticularly to the use of separated phosphatic clays as a soil wettingagent to aid in the retention of water in sandy soil, and/or forprevention or reduction of leaching of nutrients. The phosphatic clayscan be delivered to the soil as a sprinkle-on product, spray-on product,soil amendment, fertilizer or seed coating, or fertilizer composition.

BACKGROUND OF THE INVENTION

Vegetation, such as lawns or horticultural crops, grown in areas wherethe soil structure prevents the ready absorption of moisture can resultin excess irrigation water runoff due to water penetration becomingincreasingly more difficult due to the sun's hardening of the soilssurface and creating hydrophobic conditions in which the soil becomesunable to rapidly absorb water. As the soil becomes increasinglyhydrophobic, the soil begins to repel much needed water from enteringinto the soil profile.

Vegetation, such as lawns or horticultural crops, grown in areas wherethe soil structure prevents or inhibits the retention of moisture canresult in excess irrigation water requirements due to the water simplydraining out of the soil profile too quickly, which results in need toconstantly reapply moisture. This is typical of soils with high sand(quartz) content.

With respect to seed, seeds planted in soils that have characteristicsoutlined above, i.e. soils that are either hydrophobic or are unable toretain or have difficulty retaining moisture, can have their germinationimpeded, or they may require excessive watering to survive.

This can result in excessive use of water and potentially harmfulrun-off. The run-off can include plant nutrients, insecticides,fungicides, and herbicides, which can cause greater loss of cropproductivity, and to the environment if such items are found in surfacewater reservoirs. Furthermore, this ineffective use of water can createhigher demands on the water source used for irrigation.

During periods of drought, the lack of soil moisture results in plantsundergoing moisture stress due to lack of soil moisture which willresult in plant wilting, yield losses and ultimately death of the plant.At the same time this stress can increase the pathway for insect anddisease infections and competition of more drought resistant weeds.

Soil wetting agents, or surfactants, are often introduced to the soilprofile to help alleviate the issue of moisture absorption and/orretention of the soil, thereby increase the effectiveness of the watersuch that less is needed. Soil wetting agents work by lowering thecohesive and/or adhesive surface water tension and by absorbing andretaining water in the soil profile. This reduction of surface tensionallows the water to spread out more evenly and allows for betterpenetration into the soils, and retention in the soil profile, includinghydrophobic soils, or sandy soils, as well as more effective use ofwater.

Soil wetting agents can be polymer-based. These synthetic wetting agentsare a relatively expensive product (compared to standard soilamendments), thereby possibly limiting their application, in additionpolymers can over time degrade.

Naturally occurring clays have a natural affinity to water, and have ahigh water holding capacity. This is due to its extensive ability tobind water and to establish coherent structures in dry conditions.Clays, in addition to increasing water retention in soil, can provideplants with certain nutrients. Clays have been used as a wetting agentadmixed with soils, such as described, for example, in U.S. PatentApplication Publication No. 2010/0135733, and U.S. Pat. No. 4,810,280.However, prior art systems of admixing clays typically required largeamounts of clay to be incorporated which is difficult and expensive tomanufacture, require shipment of clay if the clay is not close at handto the manufacturing site, or can cause dusting or attrition issues.

There remains a need for a readily-available source of clay for use as asoil wetting agent with sufficient water holding capacity.

SUMMARY OF THE INVENTION

Embodiments of the present invention solve many of the drawbacks of theprior art wetting agents described above. According to embodiments ofthe invention, phosphatic clays are used as a wetting agent in soils,particularly hydrophobic or sandy soils. Due to its unique particle sizeand shape, phosphatic clay exhibits higher water absorbing and retainingqualities than other clays used as wetting agents. Compared to thesynthetic wetting agents of the prior art, phosphatic clays have closeto infinite capacity to retain and then release water over time and willonly loose capacity through organic material dilution over time.

Further, phosphatic clay is readily available as a by-product of miningof phosphatic ore. Phosphatic clay occurs in a matrix of sand, clay, andphosphate ore. The phosphatic clay wetting agents increase theeffectiveness of the water applied to the soil, thereby reducing theamount of run-off, and reducing the amount of water needed to accomplishsufficient irrigation.

In one embodiment, a phosphatic clay product comprises a spray-onemulsion of phosphatic clay in water for use as a wetting agent. Theemulsion is topically sprayed onto a soil, such as metered through ahose attachable spray pack. Alternatively, a dry broadcast of phosphaticclay can be applied topically to a soil. In either application, thephosphatic clay product acts as a wetting agent by penetrating, at a lowconcentration, through the foliage, and entering the root zone of aplant, where it will remain and absorb water to sufficiently supply thefoliage.

In an alternative embodiment of the invention, a phosphatic clay productcomprises a fertilizer granule or seed having a coating includingphosphatic clay particulates. This coating application allows thefertilizer or seed to attract and retain water molecules around thefertilizer granule or seed itself, thereby altering the micro soilenvironment, as opposed to the entire soil profile, to improve planthealth, increase plant growth, and/or restrict leaching of nutrientsaway from the fertilizer granule or seed.

In yet another embodiment of the invention, a phosphatic clay productcomprises a soil amendment or blend comprising a soil, such as a topsoil, admixed with phosphatic clay. This application acts as a wettingagent by penetrating, at a high concentration, through the soil profile,where it will remain and absorb water to sufficiently supply thevegetation planted within the soil, thereby altering the soil profile ofa general area.

Phosphatic clays are a byproduct of the beneficiation process of miningphosphatic ore. More specifically, the mined phosphate occurs in amatrix of sand, clay, and phosphate ore, typically in equal proportions.The clay portion is washed from the matrix in the beneficiation process.The clays are typically managed as a waste product, and are pumped tolarge settling areas at about 3 to about 5% clay solids, typically atrates of 20,000 to 80,000 gpm, where clays are allowed to settle out ofsuspension, or consolidate, typically to 12 to 15% solids. Thesesettling areas can range in size from about 300 to 800 acres.

Embodiments of the present invention, in addition to the advantages withrespect to adverse growing conditions, can alleviate or reduce the needfor large clay settling areas, and can make better use of the energy andwater used in the separation of clay/sand and phosphate ore in thebeneficiation process, thereby providing additional environmentalbenefits.

Phosphatic clays products according to embodiments of the invention canbe used to enhance soils for any of a number of uses such as, forexample, agricultural purposes, such as for growing crops or gardens,residential or commercial lawns, sporting fields or turfs such as golfcourses, sports fields, sods, or any of a variety of non-limiting uses.

The above summary of the various representative embodiments of theinvention is not intended to describe each illustrated embodiment orevery implementation of the invention. Rather, the embodiments arechosen and described so that others skilled in the art can appreciateand understand the principles and practices of the invention.

DETAILED DESCRIPTION

According to embodiments of the invention, phosphatic clay isincorporated in various forms to a soil profile of an otherwise adverseregion to aid in water absorption and retention of the soil (particularsandy soils), and/or to prevent or reduce leaching of nutrients fromseed or fertilizer, thereby improving plant health and increasing plantgrowth. Furthermore, by utilizing the phosphatic clay byproduct ofphosphatic ore mining operations, the need for large clay settling areasis reduced. In the most preferred cases, the phosphatic clay byproductfrom mining operations in a certain geographic area or region isutilized to improve the soil and/or growing conditions of the same areaor region.

In embodiments, mined phosphate ore is “washed” as part of abeneficiation process. Following the washing step, a dilute clay slurryis rendered in which the solids are suspended in a liquid carrier suchas water, initially containing from about two or three weight percentsolids to about five or six weight percent solids. Optionally, thisslurry can be pumped to large settling ponds for dewatering andconsolidation, thereby rendering a higher concentrated slurry and/or dryclay product. As described above, these clays are not pure and cancontain fine, unrecoverable particles of the mined phosphate mineral,such as apatite, and clay-sized particles of dolomite, calcite, silica,and the like, in addition to clay minerals. The clays can also containsmall amounts of metals and radionuclides. Specifically, the compositionof phosphatic clay can include, for example about 50-60% clay, 30-40%quartz, and 2-5% heavy minerals and miscellaneous components, such asthe radionuclides.

Phosphatic clays have a fine grain size, comprising an averageparticulate size of about 4 μm (0.00015 in.) or less, compared to thegrain size of silt which is from about 4 μm (0.00015 in.) to about 62 μm(0.0025 in.). More particularly, phosphatic clays are made up of clayparticles having a particle size of less than two to four μm, with abouthalf by weight of particles making up a finer fraction of less than 0.2μm. The phosphate mineral, such as in the form of apatite, make up forthese medium size fractions while the clay minerals, such asmontmorillonite, make up these finer fractions.

In one embodiment of the invention, a phosphatic clay product comprisesa naturally occurring emulsion or clay suspension of phosphatic clay.The phosphatic clay product is then applied to a region, such as a sandysoil region. For example, the phosphatic clay product can be meteredthrough a hose attachable spray pack. The phosphatic clay product isapplied directly to soil area such that the phosphatic clay product willpenetrate through the foliage, at low concentration, and enter the rootzone of the plant. It then acts locally as a soil wetting agent at theroot zone where it will remain and absorb and retain water so that wateris consistently available to the plant, regardless of whether moistureis available in the surrounding environment.

In another embodiment of the invention, a phosphatic clay productcomprises a “dry” (handleable) product comprising phosphatic clay grainsor particles or granules. In this embodiment, a phosphatic clay slurryis dewatered such that it is available in dried or solid form, such thatit can be used as a dry sprinkle, taking advantage of the very finegrain size of phosphatic clay. This clay is then easily dispersed over asoil region where it will remain and absorb and retain water so thatwater is consistently available to the root zones of plants, regardlessof whether moisture is available in the surrounding environment.

In yet another embodiment of the invention, a phosphatic clay productcomprises a soil amendment, i.e. clay grains or particles admixed withsoil. In this embodiment, phosphatic clay, available as a slurry or indried form, is mixed with soil, such as a sandy soil. The mixed soil isapplied to a region, topically or otherwise. The clay particlesdispersed through the soil remain within the soil and thereforethroughout the soil profile, to absorb and retain water throughout thesoil profile so that water is consistently available to the root zonesof plants.

In another embodiment of the invention, a phosphatic clay productcomprises a base fertilizer granule coated with phosphatic clay. Thebase fertilizer granules can comprise, for example, phosphatefertilizers, potash or complete NPK formulations, and other specialtyblends. In one particular example, the fertilizer granules compriseMicroEssentials® brand fertilizer available from the assignee of thepresent application. In another example, the fertilizer granulescomprise K-Mag® brand fertilizer granules, available from the assigneeof the present application.

A coating of phosphatic clay is distributed on an outer surface of eachof the fertilizer granules. The coating can be formed, for example, byapplying a slurry of phosphatic clay to at least a portion of the outersurface of the fertilizer granule. The slurry is dried, thereby leavinga coating of dried phosphatic clay. In one non-limiting embodiment, theclay coating can comprise about 0.1 to about 10.0 weight percent of theentire fertilizer granule on a dry basis, and more particularly fromabout 0.5 to about 2.0 weight percent. However, other coating weightscan be contemplated including less than about 0.1 or 0.5 weight percentand more than 2.0 or 10.0 weight percent. This product allows forattraction and retention of water around the individual fertilizergranules, to alter the local soil environment, i.e. soil proximate thefertilizer granule to improve plant health, increase plant growth, andprevent or reducing leaching of nutrients away from the fertilizergranule.

Alternatively to fertilizer granules, seed granules can be coated withphosphatic clay to improve plant health because the clay absorbs andretains water around the individual seed, and similarly to prevent orreduce leaching of nutrients from the seed.

In yet another alternative embodiment of the invention, phosphatic clayis directly incorporated to the fertilizer composition, as opposed to orin addition to the phosphatic clay coating. The incorporated clay cancomprise 0.1 to about 10.0 weight percent of the entire fertilizergranule on a dry basis, and more particularly from about 0.5 to about2.0 weight percent. However, other coating weights can be contemplatedincluding less than about 0.1 or 0.5 weight percent and more than 2.0 or10.0 weight percent. Similar to the embodiment above, the fertilizerscan comprise any of a variety of fertilizer types, including, but notlimited to, varieties of NPK fertilizers including phosphate-basedfertilizers, potassium-based or potash-based fertilizers, nitrogen-basedfertilizers such as urea fertilizers, K-Mag®-brand fertilizers,MicroEssentials®-brand fertilizers, or the like. This allows for theprevention or reduction of leaching of nutrients from the fertilizergranule.

Compared to the commercially available synthetic soil wetting agent, thephosphatic clay products according to embodiments of the presentinvention have more uniform performance characteristics, are cheaper toproduce, and will not break down as quickly. Further, due to theinherent fine grain size of phosphatic clay, which comprises an averageparticulate size of about 4 μm (0.00015 in.) or less (compared to thegrain size of silt which is from about 4 μm (0.00015 in.) to about 62 μm(0.0025 in.), the phosphatic clay, when used in its dry form such as adry sprinkle or as a soil amendment, will more easily infiltrate thesoil.

Other advantages to using phosphatic clays is that by utilizing thealready-produced byproduct of phosphate mining, there is the potentialto alleviate or reduce the need for large clay settling areas, and tomake better use of energy and water used in separating clay and sand andphosphate ore in the beneficiation process of phosphate ore mining.

While the invention is amenable to various modifications and alternativeforms, specifics thereof have been shown by way of example in thedrawings and described in detail. It is understood, however, that theintention is not to limit the invention to the particular embodimentsdescribed. On the contrary, the intention is to cover all modifications,equivalents, and alternatives falling within the spirit and scope of theinvention as defined by the appended claims.

The invention claimed is:
 1. A soil wetting agent composition foraltering moisture retention qualities of soil, the soil wetting agentcomprising: a carrier, wherein the carrier comprises fertilizer granulesformed form a compacted and/or granulated fertilizer material; and aphosphatic clay source incorporated within the carrier, the phosphaticclay source including dry phosphatic clay grains having an average claygrain particulate size of about 4 μm or less, wherein the phosphaticclay source is incorporated into the fertilizer material duringgranulation and/or compaction such that individual fertilizer granulescontain phosphatic clay grains throughout each granule.
 2. The soilwetting agent composition of claim 1, wherein the phosphatic clay sourcecomprises the phosphatic clay grains and at least one material selectedfrom the group consisting of: mined phosphate mineral particulates;filler mineral grains; at least one elemental metal; and at least oneradionuclide.
 3. The soil wetting agent composition of claim 1, whereinthe fertilizer granules comprise at least one source of a primarynutrient and at least one source of a micronutrient.
 4. A soil wettingagent composition for altering moisture retention qualities of soil, thesoil wetting agent comprising: a carrier, wherein the carrier comprisesa plurality of base fertilizer granules; and a phosphatic clay sourceincorporated on the carrier, the phosphatic clay source including dryphosphatic clay grains having an average clay grain particulate size ofabout 4 μm or less, wherein the phosphatic clay source comprises aphosphatic clay coating covering at least a portion of an exterior ofeach of the base fertilizer granules.
 5. The soil wetting agentcomposition of claim 4, wherein the phosphatic clay coating is formedfrom a phosphatic clay slurry including a liquid carrier in which thephosphatic clay grains are suspended, and wherein the phosphatic clayslurry is topically applied to the base fertilizer granules and dried toextract the liquid carrier and leave the phosphatic clay coatingcomprising the dry phosphatic clay grains on the base fertilizergranule.
 6. The soil wetting agent composition of claim 5, wherein thephosphate clay grains comprises about 2 wt. percent to about 5 wt.percent of the phosphatic clay slurry.
 7. The soil wetting agentcomposition of claim 5, wherein the phosphatic clay coating comprisesabout 0.1 to about 10 weight percent of the total fertilizer granule. 8.The soil wetting agent composition of claim 5, wherein the basefertilizer granule comprises at least one primary nutrient and at leastone micronutrient incorporated therein.
 9. The soil wetting agentcomposition of claim 4, wherein the phosphatic clay source comprises thephosphatic clay grains and at least one material selected from the groupconsisting of: mined phosphate mineral particulates; filler mineralgrains; at least one elemental metal; and at least one radionuclide. 10.A soil wetting agent composition for altering moisture retentionqualities of soil, the soil wetting agent comprising: a carrier, whereinthe carrier comprises a plurality of seeds; and a phosphatic clay sourceincorporated on the carrier, the phosphatic clay source including dryphosphatic clay grains having an average clay grain particulate size ofabout 4 μm or less, wherein the phosphatic clay source comprises aphosphatic clay coating covering at least a portion of an exterior ofeach of the seeds.
 11. The soil wetting agent composition of claim 10,wherein the phosphatic clay source comprises the phosphatic clay grainsand at least one material selected from the group consisting of: minedphosphate mineral particulates; filler mineral grains; at least oneelemental metal; and at least one radionuclide.
 12. A method ofproducing a soil wetting agent, the method comprising: providing aphosphatic clay slurry including phosphatic clay grains having anaverage clay grain particulate size of about 4 μm or less suspended in aliquid carrier; applying the phosphatic clay slurry to a plurality ofbase fertilizer granules or seeds; and drying the phosphatic clay slurryto extract the liquid carrier therefrom after applying the phosphaticclay slurry to the base fertilizer granules or seeds, thereby generatinga dry coating of the phosphatic clay grains covering at least a portionof an exterior of each fertilizer granule or seed as the soil wettingagent.
 13. The method of claim 12, wherein the phosphate clay grainscomprises about 2 wt. percent to about 5 wt. percent of the phosphaticclay slurry.
 14. The method of claim 12, wherein the dry coatingcomprises about 0.1 to about 10 weight percent of the total fertilizergranule or seed.
 15. A method of producing a soil wetting agent, themethod comprising: providing a phosphatic clay slurry includingphosphatic clay grains having an average clay grain particulate size ofabout 4 μm or less suspended in a liquid carrier; drying the phosphaticclay slurry to extract liquid therefrom to generate a dried phosphaticclay source as the soil wetting agent; formulating a base fertilizercomposition; granulating the base fertilizer composition in a granulatorto form fertilizer granules; and adding the dried phosphatic clay sourceto the granulator during granulation, such that the phosphate claygrains are distributed throughout the individual fertilizer granules.16. The method of claim 15, wherein the base fertilizer granulecomposition comprises at least one source of a primary nutrient and atleast one source of a micronutrient.